Hydraulic cements are cements that can set under water. This setting property serves a variety of purposes. Hydraulic cements are often used in placement of pipes or casings within a well bore of a subterranean formation for the construction of oil and gas wells. In the oil and gas industry, successful cementing of well pipe and casing during oil and gas well completion sometimes requires cement slurries which need to be of a density that is much lower than that which the cement was originally designed for by the cement manufacturer. To achieve such low densities, there is often employed the addition of large amounts of water to the existing slurry. The amount of mixing water utilized is dependent upon the desired ultimate density for the slurry as well as the API classification of the cement. However, when the addition of mixing water is employed for lowering the density of the water-cement slurry, there is experienced a detrimental effect on several properties of the resulting slurry including that of an increase of free fluid.
Thus, there exists a need in the hydraulic cementing industry for an improved well cementing composition which will provide a desired low density system while avoiding the problem of free fluid formation.
It is thus an object of the present invention to provide a novel low density well-cement slurry system which is essentially free of the problem of free fluid formation.
Another object of this invention is to provide an improved system for the cementing of subterranean wells.
Other aspects, objects and the several advantages of this invention will be apparent from the following specification and appended claims.